HVACR systems can include furnaces for heating air. The HVACR system may then heat a building (e.g., residential home, commercial building, office building, etc.) by transferring the heated air to different locations throughout the building. A heat source for the HVACR system may be the combustion reaction of a fuel (e.g., natural gas, etc.). In such a system, the hot and harmful combustion gases may flow through a heat exchanger tube and the process fluid (e.g., air, etc.) may be heated as it flows over the outside surface of the heat exchange tube. A HVACR system may employ a multi-pass heat exchanger to transfer the heat from the hot combustion products to the air. The multi-pass heat exchanger may provide a heat exchanger tube having two or more passes through the heat exchange volume of the heat exchanger (e.g., multi-pass).